Method for shielding a substrate from electromagnetic interference

Abstract

A method for shielding a substrate from electromagnetic interference is provided including providing an electromagnetic interference (EMI) shielding composition to the substrate. The EMI shielding composition comprises a reactive organic compound and a conductive filler that, during the cure of the organic compound, is capable of self-assembling into a heterogeneous structure comprised of a continuous, three-dimensional network of metal situated among (continuous or semi-continuous) polymer rich domains. The resulting composition has exceptionally high thermal and electrical conductivity.

1 . A method for shielding a substrate from electromagnetic interference comprising providing a substrate, providing an electromagnetic interference (EMI) shielding composition to the substrate, wherein the electromagnetic interference shielding composition comprises a filled, curable material capable of self-assembling to form conductive pathways during a cure process. 
     
     
         2 . The method of  claim 1 , wherein the curable material comprises a curable organic compound and a filler. 
     
     
         3 . The method of  claim 2 , wherein the filler and the organic compound exhibit an interaction during the cure of the organic compound, said interaction causing the filler to self-assemble into conductive pathways. 
     
     
         4 . The method of  claim 1 , wherein the composition is cured thereby forming conductive pathways therethrough. 
     
     
         5 . The method of  claim 1 , wherein the curable composition comprises an epoxy resin, and epoxy curative, and a fatty acid coated conductive filler. 
     
     
         6 . The method of  claim 5 , wherein the epoxy resin comprises diglycidyl ether of bisphenol F. 
     
     
         7 . The method of  claim 5 , wherein the epoxy curative comprises a polyamine anhydride adduct based on reaction between phthalic anhydride and diethylenetriamine. 
     
     
         8 . The method of  claim 1 , wherein the composition comprises an electrically conductive filler. 
     
     
         9 . The method of  claim 1 , wherein the filler is coated with a non-polar coating. 
     
     
         10 . The method of  claim 9 , wherein the non-polar coating comprises stearic acid. 
     
     
         11 . The method of  claim 1 , wherein the filler particles are sinterable to form sintered conductive pathways after self-assembly curing the cure. 
     
     
         12 . The method of  claim 1 , wherein the composition is applied to the substrate in a predetermined pattern comprising a predefined line thickness and a predefined aperture size. 
     
     
         13 . The method of  claim 12 , wherein the composition as applied to the substrate is optically transparent. 
     
     
         14 . The method of  claim 1 , wherein said composition has a shielding effectiveness of at least 20 dB between about 1 MHz and about 40 GHz. 
     
     
         15 . The method of  claim 1 , wherein the composition provides a shielding effectiveness of at least about 80 dB between about 1 MHz and about 40 GHz. 
     
     
         16 . The method of  claim 1 , wherein the composition comprises less than 40 volume percent conductive filler. 
     
     
         17 . The method of  claim 1 , wherein the composition comprises less than 15 volume percent conductive filler. 
     
     
         18 . The method of  claim 1 , wherein said composition provides further protection from electromagnetic pulses. 
     
     
         19 . The method of  claim 1 , wherein said substrate comprises at least a portion of an enclosure housing an electronic device. 
     
     
         20 . The method of  claim 19 , wherein said enclosure comprises a microelectronic circuit. 
     
     
         21 . The method of  claim 19 , wherein said enclosure comprises a vehicle. 
     
     
         22 . The method of  claim 1 , wherein the self-assembled material further provides a path to ground for at least one electrical device. 
     
     
         23 . The method of  claim 1 , wherein the composition is spray applied. 
     
     
         24 . The method of  claim 1 , wherein the composition is formed into a B-staged film prior to application to the substrate. 
     
     
         25 . The method of  claim 1 , wherein the step of providing an EMI shielding composition to a substrate comprises:
 identifying a damaged section of an EMI shielding system comprising at least one discontinuous conductive pathway;   depositing the EMI shielding composition onto the damaged section; and,   curing the deposited composition to provide at least one self-assembled conductive pathway completing the at least one discontinuous conductive pathway in the damaged section.   
     
     
         26 . The method of  claim 25 , wherein the EMI protection system comprises at least one of a conductive sheet metal, metal foil, metal mesh, carbon-metal fiber co-weaves, metalized carbon, or filled conductive polymer. 
     
     
         27 . The method of  claim 25 , wherein the EMI shielding system comprises a filled, curable material capable of self-assembling to form conductive pathways during a cure process. 
     
     
         28 . A method for non-destructive testing of an EMI shielding material comprising;
 providing an electrically conductive composition capable of providing EMI shielding;   measuring an electrical property of the composition; and,   equating the measured electrical property of the composition with the electrical conductivity of a previously degraded sample of the composition to determine the degree of degradation of the composite.   
     
     
         29 . The method of  claim 28 , wherein the composition comprises a curable material capable of self-assembling to form conductive pathways during a cure process. 
     
     
         30 . The method of  claim 28 , wherein the electrical property comprises electrical resistivity.